1. Field of the Invention
The present invention relates to an internal combustion engine with reduced noxious content in the exhaust gas. Nitrogen oxides (NO.sub.x) are reduced and the rate of fuel consumption is improved.
2. Description of the Prior Art
Today internal combustion engines for automobiles are required not only to clean the exhaust gas but also to consume as little fuel as possible. For these requirements, an exhaust gas recirculation (EGR) system is provided and lean combustion is employed. In order to prevent combustion fluctuations and misfiring in such engines, it has been proposed to increase the burning velocity.
In order to increase this burning velocity, there have been recently proposed several intake systems, in which a sub-suction path is provided separately from the main suction path and is made to inject a gas into a combustion chamber to generate a swirl of the suction gas in the combustion chamber.
However, present engines having intake systems provided with a sub-suction path are still under development and are not presently satisfactory. In fact, the prior art internal combustion engines do not have a sufficiently intense swirl. This causes a limit on lean combustion, if exhaust gas recirculation is performed in preference to exhaust emission control, especially, for the reduction of the NO.sub.x. In these prior examples, significant improvement in the rate of fuel consumption is not achieved.
On the other hand, in order to generate an intense swirl in the combustion chamber by the use of the sub-suction path, it is necessary to orient the direction of the outlet end of the sub-suction path. However, the construction of the outlet end of the sub-suction path in a predetermined direction is very difficult in production.